הממיר

CURRENCIES = {
    'USD': 1,
    'EUR': 1.06,
    'YEN': 0.0067,
    'GBP': 1.23,
    'AUD': 0.64,
    'CAD': 0.74
}


def to_usd(from_currency, amount):
    if from_currency not in CURRENCIES:
        raise Exception(f'{from_currency} is not supported')
    elif amount < 0:
        raise Exception(f'Invalid amount')
    else:
        res = CURRENCIES[from_currency] * amount
        return res


def from_usd(to_currency, amount):
    if to_currency not in CURRENCIES:
        raise Exception(f'{to_currency} is not supported')
    elif amount < 0:
        raise Exception(f'Invalid amount')
    else:
        res = amount / CURRENCIES[to_currency]
        return round(res, 4)